Bond Behavior of Steel Rebar Embedded in Cementitious Composites Containing Polyvinyl Alcohol (PVA) Fibers and Carbon Nanotubes (CNTs).

In this study, pull-out tests were conducted to investigate the bond behavior of a rebar embedded in cementitious composites with polyvinyl alcohol (PVA) fibers and carbon nanotubes (CNTs). In the cementitious composites, the binder consisted of ordinary Portland cement, blast furnace slag, and fly ash, with a weight ratio of 39.5, 21.0 and 39.5%, respectively, while the nonbinder consisted of quartzite sand, lightweight aggregate, superplasticizer, and shrinkage-reducing admixture. The water/binder ratio and volume fractions of the PVA fibers were 32.9% and 2.07%, respectively. In the test program, the rebar diameter (D13, D16, and D19) and CNTs mix ratio (0.0, 0.1, 0.2, and 0.3 wt.%) were considered as the test variables. The test results showed that the bond strength of a rebar increased as the rebar diameter decreased or as the CNTs mix ratio increased. Based on the test results, a new, simple model has been proposed with consideration of the rebar diameter, as well as the CNTs mix ratio. Comparing the test results, it was investigated that the proposed model generally represented the bond behavior well, including the bond strength and the corresponding slip of a rebar embedded in PVA cementitious composites, with or without CNTs.

Automatic Recognition of Road Damage Based on Lightweight Attentional Convolutional Neural Network.

An efficient road damage detection system can reduce the risk of road defects to motorists and road maintenance costs to traffic management authorities, for which a lightweight end-to-end road damage detection network is proposed in this paper, aiming at fast and automatic accurate identification and classification of multiple types of road damage. The proposed technique consists of a backbone network based on a combination of lightweight feature detection modules constituted with a multi-scale feature fusion network, which is more beneficial for target identification and classification at different distances and angles than other studies. An embedded lightweight attention module was also developed that can enhance feature information by assigning weights to multi-scale convolutional kernels to improve detection accuracy with fewer parameters. The proposed model generally has higher performance and fewer parameters than other representative models. According to our practice tests, it can identify many types of road damage based on the images captured by vehicle cameras and meet the real-time detection required when piggybacking on mobile systems.

Probabilistic Analysis for Strain-Hardening Behavior of High-Performance Fiber-Reinforced Concrete.

The practical application of fiber-reinforced concrete (FRC) in structural components has gained growing interest due to structural advantages such as improved tensile strength, distributed load transfer, crack width control, as well as superior durability. To this end, reliable structural assessment techniques and analytical models have been developed, placing emphasis on tension-softening behavior owing to the bond and pull-out mechanisms of fibers at a local crack. However, these models could not be directly applicable to evaluate the multiple cracking mechanisms of high-performance fiber-reinforced concrete (HPFRC), which exhibits strain-hardening behavior. To overcome this challenge, this paper presents a probabilistic analytical technique. This approach has employed the simplified diverse embedment model (SDEM). Then, an HPFRC member was modeled with multiple segments considering the most probable number of cracks. It was assumed that material properties had a normal probability distribution and were randomly assigned to each segment. To have reliable results, 10,000 analyses were performed for each analysis case and validated using experimental test data. Based on the analysis results, the actual strain-hardening tensile behavior of an HPFRC member could be reasonably predicted with the number of segments chosen on the basis of the fiber length.

Electrical control of terahertz frequency conversion from time-varying surfaces.

We investigate the electrical control of frequency conversion from a time-varying interdigitated photo-conductive antenna (IPCA) and time-varying metasurface in the terahertz (THz) frequency range. Ultrafast near-infrared (NIR) optical pulses rapidly modify the conductivities of the IPCA and metasurface; however, external voltages can retard this conductivity transition. Thus, external voltages can be used to control the frequency conversion process based on the interaction between the THz waves and the time-varying surfaces. In the IPCA, both frequency up- and down-conversion processes are suppressed by external voltages. However, in the metasurface, the down-conversion is dramatically suppressed by external voltages, whereas the suppression on the up-conversion is less effective.

Spectrum of MNX1 Pathogenic Variants and Associated Clinical Features in Korean Patients with Currarino Syndrome.

BACKGROUND: The major genetic cause of Currarino syndrome (CS), a congenital malformation syndrome typically characterized by sacral agenesis, anorectal malformation, and presence of a pre-sacral mass, is known to be pathogenic variants in motor neuron and pancreas homeobox 1 (MNX1), which exist in almost all familial cases and 30% of sporadic cases. Less commonly, a large deletion or a complex rearrangement involving the 7q36 region is associated with CS. We investigated the spectrum of MNX1 pathogenic variants and associated clinical features in the Korean patients with CS. METHODS: We enrolled 25 patients with CS, including 24 sporadic cases and one familial case. Direct sequencing of MNX1 and multiplex ligation-dependent probe amplification were performed. We also analyzed clinical phenotypes and evaluated genotype-phenotype correlations. RESULTS: We identified six novel variants amongst a total of six null variants, one missense variant, and one large deletion. The null variants included four frameshift variants (p.Gly98Alafs* 124, p.Gly145Alafs*77, p.Gly151Leufs*67, and p.Ala216Profs*5) and two nonsense variants (p.Tyr186* and p.Gln212*). The missense variant, p.Lys295Gln, was located in the highly-conserved homeobox domain and was predicted to be deleterious. A large deletion involving the 7q36 region was detected in one patient. Pathogenic variants in MNX1 were detected in 28% of all CS cases and 25% of sporadic cases. The clinical phenotype was variable in patients with and without pathogenic variants; no significant genotype-phenotype correlation was observed. CONCLUSIONS: This study revealed the spectrum and phenotypic variability of MNX1 pathogenic variants in the Korean population.

Analysis of clinical features of lipoblastoma in children.

OBJECTIVE: A lipoblastoma is pathologically benign but often recurs. Due to its rarity, studies are scarce. The purpose of this study was to investigate the clinical characteristics of lipoblastoma occurring in children and to detect any correlations with the expression of Ki-67. PARTICIPANTS: From 1998 to 2010, 33 patients were diagnosed with lipoblastoma at Seoul National University Children's Hospital. METHODS: Ki-67 immunohistochemistry staining of the tumor tissue was performed. RESULTS: A total of 33 patients (64% males) were enrolled in the study, with a mean age of 28 month. Eleven and 22 lesions were deep and superficial, respectively. Complete excisions were performed for 30 patients, and three underwent incomplete excisions. Two patients who underwent incomplete excision subsequently underwent a second operation due to tumor regrowth, and one patient had a recurrence despite complete excision. There was no statistically significant correlation observed between the tumor size or recurrence and the expression of Ki-67. CONCLUSIONS: Lipoblastoma requires an accurate diagnosis and operative resection to alleviate the symptoms induced by its growth. Incompletely resected tumor may regrow; therefore, complete excision is the treatment of choice. Continuous follow-up is needed to monitor for recurrence of disease, even after a complete excision.

Construction Condition and Damage Monitoring of Post-Tensioned PSC Girders Using Embedded Sensors.

The potential for monitoring the construction of post-tensioned concrete beams and detecting damage to the beams under loading conditions was investigated through an experimental program. First, embedded sensors were investigated that could measure pre-stress from the fabrication process to a failure condition. Four types of sensors were installed on a steel frame, and the applicability and the accuracy of these sensors were tested while pre-stress was applied to a tendon in the steel frame. As a result, a tri-sensor loading plate and a Fiber Bragg Grating (FBG) sensor were selected as possible candidates. With those sensors, two pre-stressed concrete flexural beams were fabricated and tested. The pre-stress of the tendons was monitored during the construction and loading processes. Through the test, it was proven that the variation in thepre-stress had been successfully monitored throughout the construction process. The losses of pre-stress that occurred during a jacking and storage process, even those which occurred inside the concrete, were measured successfully. The results of the loading test showed that tendon stress and strain within the pure span significantly increased, while the stress in areas near the anchors was almost constant. These results prove that FBG sensors installed in a middle section can be used to monitor the strain within, and the damage to pre-stressed concrete beams.

Clinical Study of Congenital Esophageal Stenosis: Comparison according to Association of Esophageal Atresia and Tracheoesophageal Fistula.

PURPOSE: Congenital esophageal atresia (CES) is a rare congenital disease. The severity of symptoms is variable; thus, diagnosis is difficult and tends to be delayed. CES is frequently accompanied by esophageal atresia (EA) with/without tracheoesophageal fistula (TEF). We investigated the characteristics of CES by reviewing our experience with CES patients and researched the differences between CES with EA-TEF and isolated CES. METHODS: A total of 31 patients underwent operations for CES were reviewed retrospectively. The patients were divided into two groups according to the association with EA-TEF, and compared the differences. RESULTS: Sixteen boys and 15 girls were included. The mean age at symptom onset was 8 months old, and the mean age at diagnosis was 21 months old. Nine patients with EA-TEF were included group A, whereas the other 22 patients were assigned to group B. There were no differences in sex, gestational age, associated anomalies and pathologic results between the groups. In group A, the age at diagnosis and age at surgery were younger than in group B despite the age at symptom occurrence being similar. Postoperative complications occurred only in group A. CONCLUSION: In this study, symptoms occurred during the weaning period, and vomiting was the most frequent symptom. CES patients with EA-TEF tended to be diagnosed and treated earlier despite the age at symptom occurrence being similar. CES patients with EA-TEF had more postoperative complications; therefore, greater attention should be paid during the postoperative period.

Autophagy plays a role in skeletal muscle mitochondrial biogenesis in an endurance exercise-trained condition.

Mitochondrial homeostasis is tightly regulated by two major processes: mitochondrial biogenesis and mitochondrial degradation by autophagy (mitophagy). Research in mitochondrial biogenesis in skeletal muscle in response to endurance exercise training has been well established, while the mechanisms regulating mitophagy and the interplay between mitochondrial biogenesis and degradation following endurance exercise training are not yet well defined. The purpose of this study was to examine the effects of a short-term inhibition of autophagy in response to acute endurance exercise on skeletal muscle mitochondrial biogenesis and dynamics in an exercise-trained condition. Male wild-type C57BL/6 mice performed five daily bouts of 1-h swimming per week for 8 weeks. In order to measure autophagy flux in mouse skeletal muscle, mice were treated with or without 2 days of 0.4 mg/kg/day intraperitoneal colchicine (blocking the degradation of autophagosomes) following swimming exercise training. The autophagic flux assay demonstrated that swimming training resulted in an increase in the autophagic flux (~100 % increase in LC3-II) in mouse skeletal muscle. Mitochondrial fusion proteins, Opa1 and MFN2, were significantly elevated, and mitochondrial fission protein, Drp1, was also increased in trained mouse skeletal muscle, suggesting that endurance exercise training promotes both mitochondrial fusion and fission processes. A mitochondrial receptor, Bnip3, was further increased in exercised muscle when treated with colchicine while Pink/Parkin protein levels were unchanged. The endurance exercise training induced increases in mitochondrial biogenesis marker proteins, SDH, COX IV, and a mitochondrial biogenesis promoting factor, PGC-1α but this effect was abolished in colchicine-treated mouse skeletal muscle. This suggests that autophagy plays an important role in mitochondrial biogenesis and this coordination between these opposing processes is involved in the cellular adaptation to endurance exercise training.

Long-term functional outcomes of PPPD in children--Nutritional status, pancreatic function, GI function and QOL.

PURPOSE: The purpose of this study was to analyze the long-term outcomes, such as nutritional status, pancreatic function, gastrointestinal (GI) function, and quality of life (QOL), in children who underwent pylorus-preserving pancreaticoduodenectomy (PPPD). METHODS: Between 1992 and 2013, there were 15 children who underwent PPPD at Seoul National University Children's Hospital, and 10 of them participated in this study. A retrospective review of the patients' medical records and follow-up was done. Their nutritional statuses were estimated by height, body weight, weight for age Z-score, body mass index (BMI), and serum protein, albumin levels. The endocrine and exocrine functions of the pancreas were estimated by diabetes mellitus (DM), steatorrhea, and Bristol stool chart. The GI function and QOL were evaluated via questionnaires. The follow-up period ranged from 3 to 18years. RESULTS: There were no severe growth disturbances, 6 patients experienced mild steatorrhea and 3 showed above the category 6 in Bristol stool chart. All the patients experienced mild GI symptoms. As for the QOL, there were no significant negative answers, except for one patient with DM. CONCLUSIONS: Almost all the study subjects, who underwent PPPD in their childhood, did not present significant problems except for one patient with DM.

Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers.

In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC) specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress-strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures.

Flexural Behavior of HPFRCC Members with Inhomogeneous Material Properties.

In this paper, the flexural behavior of High-performance Fiber-Reinforced Cementitious Composite (HPFRCC) has been investigated, especially focusing on the localization of cracks, which significantly governs the flexural behavior of HPFRCC members. From four points bending tests with HPFRCC members, it was observed that almost evenly distributed cracks formed gradually, followed by a localized crack that determined the failure of the members. In order to investigate the effect of a localized crack on the flexural behavior of HPFRCC members, an analytical procedure has been developed with the consideration of intrinsic inhomogeneous material properties of HPFRCC such as cracking and ultimate tensile strengths. From the comparison, while the predictions with homogeneous material properties overestimated flexural strength and ductility of HPFRCC members, it was found that the analysis results considering localization effect with inhomogeneous material properties showed good agreement with the test results, not only the flexural strength and ductility but also the crack widths. The test results and the developed analysis procedure presented in this paper can be usefully applied for the prediction of flexural behaviors of HPFRCC members by considering the effect of localized cracking behavior.

Neonatal gastric perforation: A single center experience.

AIM: To determine the etiology and prognostic factors for neonatal gastric perforation (NGP), a rare but life-threatening disease. METHODS: Between 1980 and 2011, nine patients underwent surgical intervention for NGP at Seoul National University Children's Hospital. The characteristics and prognosis of the patients were retrospectively analyzed. RESULTS: Among the nine patients, three (33.3%) were preterm babies and five (55.5%) had associated anomalies, which included diaphragmatic eventration (n = 2), congenital diaphragmatic hernia, esophageal atresia with tracheoesophageal fistula, and antral web. Three (33.3%) patients were born before 1990 and three (33.3%) had a birth weight < 2500 g. Pneumoperitoneum was found on preoperative images in six (66.7%) patients, and incidentally in the other three (33.3%) patients. Surgery was performed within 24 h after the onset of symptoms in seven (77.8%) patients. The overall mortality rate was 22.2% (2/9). The time between symptoms and surgical intervention was the only prognostic factor for survival, whereas premature birth and birth weight were not. CONCLUSION: Early detection and advances in neonatal intensive care may improve the prognosis of NGP.

Development and validation of web-based nomograms to predict postoperative invasive component in ductal carcinoma in situ at needle breast biopsy.

OBJECTIVES: Although sonography-guided core needle biopsy is a highly targeted method, there is a possibility of an invasive component after surgical excision of ductal carcinoma in situ (DCIS) of the breast. This study was performed to develop and validate nomograms to predict the postoperative invasive component in DCIS at core needle biopsy. METHODS: Two nomograms were developed using the data of previous meta-analysis and multivariate analysis. Nomograms were validated externally using the data of the authors' affiliation. The accuracy was validated by the expected-to-observed ratio and the Hosmer-Lemeshow goodness-of-fit test. Discrimination was validated by the area under the curve (AUC) of receiver operating characteristic (ROC) curve analysis. RESULTS: The nomogram using the meta-analysis study data was developed at http://dcis-m.surgery.kr.pe/, and the nomogram using the multivariate analysis study data was developed at http://dcis-k.surgery.kr.pe/. The Hosmer-Lemeshow goodness-of-fit test showed that the nomogram using multivariate analysis data (p = 0.131) was better calibrated than that using meta-analysis data (p < 0.001). ROC curve analysis showed statistically significant power of discrimination in both nomograms (AUC = 0.776, 0.751). CONCLUSIONS: Both nomograms showed statistically significant discriminatory power, but the nomogram using the data of multivariate analysis was simpler and more reliable. These would be useful for the prediction of invasive cancer and the need for sentinel node biopsy in DCIS at core needle biopsy.

Comparison of outcomes according to the operation for type A esophageal atresia.

PURPOSE: The purpose was to evaluate outcomes according to different operative strategies of type A esophageal atresia (EA). METHODS: All patients who underwent surgery for type A EA between 1980 and 2011 were included. Patients were divided into 2 groups: E-E group included patients who received esophageal end-to-end anastomosis, whereas E-G group included patients who received esophago-gastric tube anastomosis. RESULTS: Twenty-two patients were included. The median gestational age was 37.5 weeks. The median birth weight was 2.5 kg. Twenty-one patients underwent gastrostomy as initial procedures, and one patient underwent primary esophageal end-to-end anastomosis. The median gap between both esophageal ends was six vertebral distance (VD). Seven patients underwent primary anastomosis of the esophagus, and 14 patients underwent gastric replacement. Three patients (13.6%) had anastomotic leakage and 10 patients (45.5%) had anastomotic stenosis. Most of the patients (90.9%) had gastroesophageal reflux, but only two patients required antireflux surgery. The median VD was significantly shorter in E-E group than in E-G group (3 VD vs. 6 VD). Stenosis was significantly more often in E-E group, but there was no significant difference in leakage and reflux symptoms. CONCLUSION: The treatment for type A EA can include E-E anastomosis or E-G anastomosis, depending on the length of the end-to-end interval after performing gastrostomy. Appropriate tension and blood flow in the anastomosis site are essential for preventing postoperative stenosis and leakage, and esophageal replacement with gastric tube is believed to be feasible and safe in cases where excessive tension is present.

Long term outcomes of pediatric liver transplantation according to age.

Liver transplantation (LT) has been the key therapy for end stage liver diseases. However, LT in infancy is still understudied. From 1992 to 2010, 152 children had undergone LT in Seoul National University Hospital. Operations were performed on 43 patients aged less than 12 months (Group A) and 109 patients aged over 12 months (Group B). The mean age of the recipients was 7 months in Group A and 74 months in Group B. The patients' survival rates and post-LT complications were analyzed. The mean Pediatric End-stage Liver Disease score was higher in Group A (21.8) than in Group B (13.4) (P = 0.049). Fulminant hepatitis was less common in Group A (4.8%) than in Group B (13.8%) (P = 0.021). The post-transplant lymphoproliferative disorder and portal vein complication were more common in Group A (14.0%, 18.6%) than in Group B (1.8%, 3.7%) (P = 0.005). However, the 1, 5, and 10 yr patient survival rates were 93%, 93%, and 93%, in Group A and 92%, 90%, and 88% in Group B (P = 0.212). The survival outcome of pediatric LT is excellent and similar regardless of age. LTs in infancy are not riskier than those of children.

Effects of compression/stretching of the spermatic cord and blunt dissection on testicular growth and fertility.

PURPOSE: This study was performed to investigate whether compression/stretching of the spermatic cord or blunt dissection influences testicular development and fertility. In addition, the authors evaluated whether the extents of testicular damage differ between these 2 surgical manipulations. METHODS: Forty-four prepubertal male Sprague-Dawley (SD) rats (Harlan Sprague-Dawley Inc, Indianapolis, Ind) were divided into 3 groups: (1) the control group (CG) animals underwent a sham operation in the right groin, (2) the experimental group 1 (EG1) underwent compression/stretching of the right spermatic cord, and (3) the experimental group 2 (EG2) underwent dissection around the right spermatic cord structures. Testicular volumes, weights, mean seminiferous tubular diameters (MSTDs), mean testicular biopsy scores, and numbers of offspring and of pregnant females were evaluated. RESULTS: Right (operative) and left (nonoperative) testicular volumes were smaller in the EG2 group than in the CG or EG1 groups. Left MSTDs in the EG1 and EG2 groups increased more than in the CG group. Numbers of Sertoli cells in left testes differed in the 3 groups, in the order EG1 < CG < EG2. Mean testicular biopsy scores, offspring numbers, and pregnant female numbers were no different in the 3 groups. CONCLUSIONS: Both surgical manipulations influenced testicular growth, but they did not compromise spermatogenesis or fertility in SD rats.

Is the outcome of the left colon antegrade continence enema better than that of the right colon antegrade continence enema?

BACKGROUND/PURPOSE: The purpose of this report was to review the results of the antegrade continence enema (ACE) procedure and to compare the outcomes of right and left colon ACEs in children. METHODS: Thirty patients who underwent an ACE between 1998 and 2005 were analyzed. Data were obtained based on the following parameters: postoperative soiling, catheter insertion time, colonic washout time, quality of life, and abdominal pain during and after the ACE. Twenty-nine patients were followed for an average of 3.8 years (range, 4 months-7.3 years). RESULTS: Right colon ACEs were performed in 23 patients, and left colon ACEs were performed in 7 patients. The common complications of the ACE included abdominal pain during and after the ACE (51.7%) and stoma strictures (41.4%). The overall ACE success rate was 24/29 (82.8%; right colon ACE, 18/29; left colon ACE, 6/29). Twenty-three patients (95.8%) believed their quality of life was improved. There were no significant differences in complications or outcomes between the right and left ACEs. CONCLUSIONS: An ACE is an effective treatment for children with fecal incontinence. A left colon ACE has similar efficacy as a right colon ACE in managing fecal incontinence in children.

Vasoactive intestinal polypeptide-producing ganglioneuromatosis involving the entire colon and rectum.

Vasoactive intestinal polypeptide (VIP) is known to cause the watery diarrhea, hypokalemia, and achlorhydria syndrome. A 14-year-old girl was admitted with a 4-year history of persistent uncontrollable diarrhea and hypokalemia. Computed tomographic evaluation of the neck, chest, and abdomen were normal. Numerous polyps covering the entire colon and rectum were noted on colonoscopy. The serum VIP level was 143 pg/mL. The patient underwent a total proctocolectomy with an ileal-J-pouch. The pathologic examination revealed ganglioneuromatosis. Postoperatively, the symptoms resolved, and the serum VIP level fell to lower than 5 pg/mL. This is an unusual case of the watery diarrhea, hypokalemia, and achlorhydria syndrome caused by ganglioneuromatosis of the entire colon and rectum.

Is excision of a choledochal cyst in the neonatal period necessary?

PURPOSE: Although the incidence of choledochal cyst (CC) diagnosed in the prenatal or neonatal period is increasing, excision of CC in early infancy is not universally recommended. To validate the rationale of excision of CC in the neonatal period, operative complications and the histologic grade of liver fibrosis at the time of excision of CC were compared in three age groups. METHODS: 198 patients who underwent excision of CC, were divided into three age groups, i.e., within 30 days old (group 1, n = 11), 1 to 12 month-old (group 2, n = 40) and over 12 month-old (group 2, n = 147). Retrospective review of their medical records was performed. RESULTS: The overall operative complications were 12 (7 cholangitis, 4 bleeding, 1 ileus). No complication occurred in the group 1. The grade of liver fibrosis had statistically significant positive correlation among groups. CONCLUSION: Excision of CC in the neonatal period is a safe procedure. The grade of liver fibrosis increased with age. These results support the rationale of early excision of CC.